THE PETRELS 391 



THE PETRELS 

 [W. P. PYCRAFT] 



To those who are interested in the study of birds in relation to 

 their environment, the Petrels must always appeal strongly. By the 

 earlier ornithologists, who paid no heed to environmental conditions, 

 these birds were commonly associated with the Gulls. And with some 

 reason, if one does not look below the surface of things, for some of 

 the Petrels have an undeniably gull-like look about them, and this is 

 especially true, perhaps, of the Fulmars. But the likeness is a super- 

 ficial one only, and the further we compare the two types the more 

 obvious this becomes. The beak-sheath is the most telling of the 

 external differences, for in the Petrels which group, it must be 

 remembered, also includes the Albatrosses it is composed of 

 numerous separate pieces, of which one on each side commonly 

 forms the roof of the nostrils, sometimes the two apertures open 

 together in a common case-like or tube-like cavity, hence the name 

 "Tubinares" or "tube-nosed." The whole skeleton, the convolutions 

 of the intestines, the pterylosis, all differ markedly from Charadrii- 

 form plan, and indicate affinities with the Divers and Penguins, and, 

 more remotely, the Ciconiiform type. But besides the evidence of 

 the laboratory, we have yet other sources of information. The most 

 helpful of these concern the characters of the eggs and young. Of 

 the first, it may suffice to remark that not more than one is laid 

 during the year, and that this lacks any of the characteristics of the 

 gulls' eggs, being indeed white, or at most faintly freckled with dull 

 red. As touching the young, a moment's glance will show how 

 absolutely unlike are the young Gull and the young Petrel. Young 

 Gulls are nidifugous, and have the down-feathers short and indistinctly 

 striped or mottled. Young Petrels, on the other hand, are nidicolous, 

 and are covered with exceptionally long down, which is either white, 



